var previouslyOpened = '';


function extrabuch_t( id ) {

	var elem = document.getElementById( id );
	if ( elem && elem.parentNode ) {

		if ( elem.style.display == "block" ) {

			if ( previouslyOpened == id )
				previouslyOpened = '';

			elem.style.display = "none";

		} else {

			if ( previouslyOpened ) {

				var elemPrev = document.getElementById( previouslyOpened );
				if ( elemPrev )
					elemPrev.style.display = "none";

			}

			elem.style.display = "block";

			previouslyOpened = id;

		}
	}
}